Discharge device and machine

Abstract

The invention relates to a discharge device (10) for discharging electrostatic charge from a shaft (11), comprising a holder (12), a spring element (20) arranged on the holder and at least one conductor (37, 38) arranged on the spring element and extending transversely to a shaft longitudinal axis (17), wherein the conductor has a shaft contact section (39, 40) for contacting a circumferential contact area (41, 42) of a shaft circumference (43), such that the shaft contact section is arranged tangentially to the shaft circumference when in contact with the shaft circumference.

Description

[0001] The invention relates to a dissipation device for dissipating electrostatic charge from a shaft. Furthermore, the invention relates to a machine comprising a dissipation device.

[0002] Such a discharge device is well known in the art and serves to discharge electrostatic charge or electrical currents from a shaft of a machine, whereby undesired current flow via bearing points of the shaft and associated bearing damage can be avoided.

[0003] EP 3 044 840 B1 discloses a dissipation device for dissipating electrostatic charge from a shaft, comprising a flexurally elastic conductor having a carbon fiber arrangement with at least two conductor sections arranged on a holder, extending transversely to a shaft longitudinal axis and insulated from the holder, which conductor sections can be connected to an earthing conductor via their section ends accommodated in the holder, wherein the conductor sections each have a shaft contact section, and the shaft contact sections together form a contact arrangement for contacting two circumferential contact regions of a shaft circumference arranged opposite one another in a shaft contact plane, such that the shaft contact sections are arranged tangentially to the shaft circumference when in contact with the shaft circumference.The section ends are preferably integrally connected to one another via a connecting section, which serves for connection to the grounding conductor. Due to the flexible design of the conductor sections, the shaft contact sections bear against the shaft circumference with a contact force in the circumferential contact areas.

[0004] A disadvantage of the discharge device described above is that the contact force that can be formed by means of the flexible conductor is generally not high enough to achieve sufficient discharge of electrostatic charge from the shaft via the discharge device, so that bearing damage cannot be reliably avoided in a machine despite the provision of the discharge device.

[0005] The present invention is therefore based on the object of proposing a discharge device and a machine by means of which bearing damage can be reliably avoided.

[0006] This object is achieved by a discharge device having the features of claim 1 and a machine having the features of claim 17.

[0007] The dissipation device according to the invention for dissipating electrostatic charge from a shaft comprises a holder, a spring element arranged on the holder and at least one conductor arranged on the spring element and extending transversely to a shaft longitudinal axis, wherein the conductor has a shaft contact section for contacting a circumferential contact region of a shaft circumference, such that the shaft contact section is arranged tangentially to the shaft circumference when in contact with the shaft circumference.

[0008] Accordingly, the invention provides that the discharge device comprises at least one conductor which is arranged on the holder via a spring element, preferably designed as a single piece, which also comprises the discharge device, wherein the provision of the spring element, in particular the associated possibility of forming the spring element from a suitable material in order to achieve a desired or sufficiently high restoring force or contact force completely independently of the conductor, makes it possible for the shaft contact section to bear against the shaft circumference with a comparatively higher contact force in the circumferential contact area, whereby sufficient discharge of electrostatic charge or electrical currents from the shaft via the discharge device is always enabled, so that bearing damage can be reliably avoided. The spring element is therefore designed orThe conductor can be rigid or flexible, generating a contact force with which the shaft contact section rests against the shaft circumference in the circumferential contact area.

[0009] The holder may be made of an electrically non-conductive material, in particular a plastic material.

[0010] In a preferred embodiment of the discharge device, the discharge device can comprise two conductors arranged on the spring element, extending transversely to the longitudinal axis of the shaft and formed separately from one another, wherein the conductors can each have a shaft contact section, wherein the shaft contact sections together can form a contact arrangement for contacting two circumferential contact regions of the shaft circumference arranged opposite one another in a shaft contact plane, such that the shaft contact sections can be arranged tangentially to the shaft circumference when in contact with the shaft circumference. Due to the double design of the conductors or the shaft contact sections lying tangentially against the shaft circumference at substantially opposite circumferential contact regions of the shaft circumference, the discharge device functions independently of the direction of rotation. The discharge device can also comprise more than two conductors.

[0011] Furthermore, if the discharge device comprises two or more conductors, it can comprise a separate spring element for each conductor, whereby each conductor can then be arranged on one of the spring elements. The discharge device can then therefore comprise two or more spring elements. However, the discharge device preferably comprises a single spring element, which allows for a simple design of the discharge device.

[0012] Advantageously, the holder can be designed as a plate, allowing the discharge device to be designed compactly and cost-effectively. The geometric shape of the holder or plate can, in principle, be arbitrary or suitably selected. When the discharge device is arranged on a machine or the shaft, the plate or a plate plane can extend transversely to the shaft's longitudinal axis, as viewed. The conductor(s) can then extend in a plane extending parallel to the plate or plate plane. The shaft contact plane can then therefore extend parallel to the plate or plate plane.

[0013] In a preferred embodiment of the discharge device, the holder can be U-shaped when viewed in cross-section, wherein the holder can have two leg sections and a connecting section connecting the leg sections, wherein the spring element can be arranged on the connecting section. This embodiment of the discharge device is particularly advantageous when two conductors are provided. Designing the holder as a U-shaped plate enables a particularly compact and cost-effective design of the discharge device as well as a particularly space-saving installation of the discharge device. The connecting section offers an advantageous possibility of fastening the spring element to the holder. Viewed in a front view of the discharge device, each of the conductors can extend substantially over, in alignment with, or along one of the leg sections.Furthermore, a hole can be formed in each leg section, whereby the holes can serve for attaching the discharge device or for arranging the discharge device on the machine or shaft. Instead of a U-shape, the holder or plate can also be designed, for example, with a V-shape, rectangular shape, or circular shape. In general, holes can be formed in the holder or plate for attaching the discharge device or for arranging the discharge device on the machine or shaft.

[0014] Advantageously, an intermediate space delimited by the leg sections and the connecting section can be designed for the shaft to pass through or can be passed through by the shaft or, when the discharge device is arranged on the machine or shaft, can be passed through by the shaft, so that the leg sections and the connecting section can surround the shaft circumferentially in sections, whereby the discharge device can be installed in a particularly space-saving manner. A radial inner side of the holder facing the shaft can then have a circular profile at least in sections, i.e. be adapted to a circular cross-sectional shape of the shaft. If the holder or the plate is designed with a rectangular or circular shape, a preferably circular passage formed in the holder can be passed through by the shaft.If a V-shape is provided for the plate, a gap defined by two leg sections of the holder can be penetrated by the shaft.

[0015] Advantageously, the holder can have a recessed area on the radial inner side of the holder in the region of the connecting section, intended for accommodating the spring element in sections. The recessed area can accommodate the spring element arranged on the connecting section in sections and thus secure it against displacement, particularly along the connecting section.

[0016] Advantageously, the spring element can be detachably attached to the holder, preferably by screwing. The spring element can then also be easily replaced. The discharge device can comprise a screw by means of which the spring element can be screwed to the holder. However, in addition to the detachable attachment, other types of attachment are also conceivable, for example, by riveting or gluing.

[0017] Advantageously, the spring element can be attached to the holder by means of a fastening means of the discharge device, preferably the screw means, wherein the fastening means or screw means can further be provided for attaching a grounding conductor to the spring element. The fastening means or screw means can then simultaneously serve to attach the spring element to the holder and to attach the grounding conductor to the spring element, so that no separate fastening means is required for attaching the grounding conductor to the spring element.

[0018] Advantageously, the spring element can be made of an electrically conductive material or a metal. The grounding conductor can then be connected to the spring element so that the electrostatic charge can pass from the conductor(s) via the spring element to the grounding conductor. The grounding conductor can be connected to the spring element using the fastening means or screw means, which can also serve to fasten the spring element to the holder. Alternatively, it can be provided that the grounding conductor is connected to the spring element via a cable lug or connection socket of the discharge device that is fastened to or connected to the spring element, or that the grounding conductor can be connected to the spring element by soldering. If the spring element is made of an electrically non-conductive material, the grounding conductor can be connected to both conductors.

[0019] Advantageously, the spring element can have a base section and at least one, preferably two, preferably arm-like, spring sections projecting preferably obliquely from the base section, wherein the conductor can be fastened to the spring section. To fasten the spring element to the holder, the base section, which can be arranged substantially on a front side of the discharge device on the connecting section, can be screwed to the connecting section by means of the screw means, which can penetrate a hole formed in the base section and a hole formed in the connecting section. The hole formed in the connecting section, together with the holes formed in the leg sections, can also serve to arrange the discharge device on the machine or shaft.If the discharge device comprises two conductors, the spring element can have two, preferably arm-like, spring sections that protrude from the base section, preferably at an angle. One of the conductors can be attached to each spring section. A force can be exerted on each conductor essentially independently of one another via the preferably arm-like spring arm sections.

[0020] Advantageously, the or each spring section can have a mounting receptacle for securing the conductor or one of the conductors. Using an end section of the conductor or end sections of the conductors, the conductor or conductors can then be inserted into the mounting receptacles and secured therein, preferably by plastically deforming or crimping the mounting receptacles together with the end sections.

[0021] Advantageously, the spring element can be made of an elastic material, preferably a spring sheet. By appropriate cutting and bending, the spring element can then be easily formed in one piece and with a desired geometry. A desired or sufficiently high contact force can be easily achieved by a suitable choice of material, in particular the spring sheet, and / or material thickness.

[0022] Advantageously, the conductor(s) can be attached to the spring element by plastic deformation, preferably crimping. This type of attachment is not only simple but also ensures secure fastening while maintaining good electrical contact between the spring element or the fastening sleeves and the conductor(s). Attachment by means of a press connection or crimp connection is also conceivable.

[0023] The conductor(s) may be made predominantly of carbon.

[0024] In a preferred embodiment of the discharge device, the conductor(s) can be formed with or from carbon fibers. The carbon fibers can be embedded in a resin matrix. Furthermore, the carbon fibers can be provided with a coating of pyrolytic carbon, which can serve not only to compact a contact surface of the conductor(s) but also to form a sheath supporting the carbon fibers. The coating can be formed, for example, using a CVI (chemical vapor infiltration) process. The conductor(s) can then be formed, in particular, with or from carbon fiber rods, carbon fiber mats, carbon fiber braids, carbon fiber foils, or the like. Instead of carbon fibers, a suitable metal, such as copper or brass, is also conceivable. Carbon-metal mixtures are also conceivable.Furthermore, any other suitable electrically conductive material is also conceivable. For example, it is conceivable to form the conductor(s) from a plastic filled with an electrically conductive material. In principle, the material from which the conductor(s) is / are made must be suitable for dissipating electrostatic charge.

[0025] Advantageously, the conductor(s) can be elongated, preferably rod-shaped. The shaft contact section(s) then has(have) a comparatively large surface area, which can increase the dissipation of the electrostatic charge.

[0026] Advantageously, if the down conductor comprises two conductors, the conductors or their longitudinal axes can be arranged obliquely or non-parallel relative to each other. However, a parallel arrangement of the conductors would also be conceivable.

[0027] Advantageously, the discharge device can be designed such that, viewed in a front view of the discharge device, the holder or an outer side of the holder projects beyond the conductor(s) in a radial direction on all sides, so that the conductor(s) do not project beyond the holder radially on the outside, whereby the discharge device can be designed even more compactly.

[0028] The machine according to the invention comprises a discharge device according to the invention. The machine can comprise a shaft.

[0029] A preferred embodiment of the invention is explained in more detail below with reference to the accompanying drawings.

[0030] They show: Fig. 1 a front view of a drainage device; Fig. 2 a perspective front view of the discharge device obliquely from one side; Fig. 3 a sectional view of the discharge device along a line shown in the Fig. 1 shown line AA; Fig. 4 a perspective rear view of the discharge device obliquely from below; Fig. 5 a perspective rear view of the drainage device; Fig. 6 a perspective front view of the drainage device; Fig. 7 a bottom view of the drainage system; Fig. 8 a front view of the drainage device; Fig. 9 a side view of the drainage device; Fig. 10 a perspective front view of the drainage device obliquely from another side; Fig. 11 a front view of a holder of the discharge device; Fig. 12 a perspective front view of the holder obliquely from one side; Fig. 13 a front view of a spring element of the discharge device; Fig. 14 a sectional view of the spring element along a line shown in the Fig. 13 shown line AA; Fig. 15 a bottom view of the spring element; Fig. 16 a partial view of the spring element.

[0031] A summary of the Fig. 1 bis 16 shows a dissipation device 10 for dissipating electrostatic charge from a shaft 11, which is in the Fig. 1is only indicated by a dashed line. The discharge device 10 comprises a holder 12 made of an electrically non-conductive material and designed as a U-shaped plate when viewed in cross-section, which holder forms two leg sections 13, 14 and a connecting section 15 connecting the leg sections 13, 14 to one another. An intermediate space 16 delimited by the leg sections 13, 14 and the connecting section 15 can be penetrated by the shaft 11 in the holder 12 which, when the discharge device 10 is arranged on the shaft 11 or a machine comprising the shaft 11, extends transversely to a shaft longitudinal axis 17, so that the leg sections 13, 14 and the connecting section 15 surround the shaft 11 in sections on the circumference. A radial inner side 18 of the holder 12 has a circular profile in sections.The discharge device 10 further comprises a spring element 20 arranged essentially on a front side 19 of the discharge device 10 on the holder 12 and formed integrally from an electrically conductive spring sheet. The spring element 20 forms a base section 21 and two arm-like spring sections 22, 23 projecting obliquely from the base section 21 in opposite directions and having fastening receptacles 24, 25 at their ends. Specifically, the spring sections 22, 23 project from a first side section 27 of the base section 21, projecting in an axial direction 26 parallel to the shaft longitudinal axis 17 beyond a central section 28 of the base section 21, wherein the spring sections 22, 23 are integrally formed on the first side section 27.To fasten the spring element 20 to the holder 12, the central section 28 arranged on the front side 19 on the connecting section 15 is screwed to the connecting section 15 by means of a screw means (not shown here), which passes through a hole 29 formed in the central section 28 and a hole 30 formed in the connecting section 15. The radial inner side 18 forms a recessed area 31 in the region of the connecting section 15 in order to accommodate a second side section 32 of the base section 21 projecting beyond the central section 28 counter to the axial direction 26, so that the spring element 20 is secured against displacement, in particular along the connecting section 15.The first side section 27 is formed on a side 33 of the middle section 28 on the middle section 28, which side is opposite a side 34 of the middle section 28, on which the second side section 32 is formed on the middle section 28. The base section 21 is Z-shaped when viewed in cross-section. By means of the screw means, a grounding conductor (not shown here) can also be fastened or connected to the spring element 20. Furthermore, a hole 35, 36 is formed at the end in each leg section 13, 14, wherein the holes 35, 36 together with the hole 30 serve to fasten the discharge device 10. Furthermore, the discharge device 10 comprises two rod-shaped elements arranged on the spring element 20, which are predominantly made of carbon and formed with carbon fibers and which, when the discharge device 10 is arranged on the shaft 11 orConductors 37, 38 extending transversely to the shaft longitudinal axis 17, viewed from the machine, wherein the conductors 37, 38 each have a shaft contact section 39, 40, wherein the shaft contact sections 39, 40 together form a contact arrangement for contacting two oppositely arranged circumferential contact regions 41, 42 of a shaft circumference 43, such that the shaft contact sections 39, 40 are arranged tangentially to the shaft circumference 43 when in contact with the shaft circumference 43. The shaft circumference 43 and the circumferential contact regions 41, 42 are also indicated by the dashed line as part of the dashed line. Each of the conductors 37, 38 is received with an end section 44, 45 in one of the fastening sleeves 24, 25 and is fastened by plastic deformation or crimping of the fastening sleeve 24, 25 together with the end section 44, 45 to the respective spring section 22, 23.The conductors 37, 38 extend on the front side 19 in a plane 46 extending parallel to the holder 12. Viewed in a front view of the discharge device 10, each of the conductors 37, 38 extends substantially over or in alignment with or along one of the leg sections 13, 14. The conductors 37, 38, which are arranged obliquely relative to one another, are arranged in a trapezoidal arrangement 47 and extend above the holder 12 at a distance from the holder 12. An axis of symmetry 48 of the trapezoidal arrangement 47 is aligned with an axis of symmetry 49 of the holder 12. In addition, a radial outer side 50 of the holder 12 projects beyond the conductors 37, 38 on all sides in a radial direction 51 extending transversely to the shaft longitudinal axis 17, viewed from the front.

Claims

1. Dissipation device (10) for dissipating electrostatic charge from a shaft (11), comprising a holder (12), a spring element (20) arranged on the holder and at least one conductor (37, 38) arranged on the spring element and extending transversely to a shaft longitudinal axis (17), wherein the conductor has a shaft contact section (39, 40) for contacting a circumferential contact region (41, 42) of a shaft circumference (43), such that the shaft contact section is arranged tangentially to the shaft circumference when in contact with the shaft circumference.

2. Discharge device according to claim 1, characterized by thatthe discharge device (10) comprises two conductors (37, 38) arranged on the spring element (20) and extending transversely to the longitudinal shaft axis (17), wherein the conductors each have a shaft contact section (39, 40), wherein the shaft contact sections together form a contact arrangement for contacting two circumferential contact regions (41, 42) of the shaft circumference (43) arranged opposite one another in a shaft contact plane, such that the shaft contact sections are arranged tangentially to the shaft circumference when in contact with the shaft circumference.

3. Discharge device according to claim 1 or 2, characterized by that the holder (12) is designed as a plate.

4. Discharge device according to one of the preceding claims, characterized by thatthe holder (12) is U-shaped when viewed in cross-section, wherein the holder has two leg sections (13, 14) and a connecting section (15) connecting the leg sections to one another, wherein the spring element (20) is arranged on the connecting section.

5. Discharge device according to claim 4, characterized by that an intermediate space (16) delimited by the leg sections (13, 14) and the connecting section (15) is designed for the shaft (11) to pass through.

6. Discharge device according to claim 4 or 5, characterized by that the holder (12) has, on a radial inner side (18) of the holder in the region of the connecting section (15), a recessed area (31) provided for sectionally receiving the spring element (20).

7. Discharge device according to one of the preceding claims, characterized by thatthe spring element (20) is detachably attached to the holder (12), preferably by screwing.

8. Discharge device according to one of the preceding claims, characterized by that the spring element (20) is fastened to the holder (12) by means of a fastening means, preferably a screw means, of the discharge device (10), wherein the fastening means is further provided for fastening an earthing conductor to the spring element.

9. Discharge device according to one of the preceding claims, characterized by that the spring element (20) is made of an electrically conductive material.

10. Discharge device according to one of the preceding claims, characterized by thatthe spring element (20) has a base section (21) and at least one, preferably two, preferably arm-like, spring sections (22, 23) projecting preferably obliquely from the base section, wherein the conductor (37, 38) is fastened to the spring section.

11. Discharge device according to claim 10, characterized by that the spring section (22, 23) has a fastening receptacle (24, 25) for fastening the conductor (37, 38).

12. Discharge device according to one of the preceding claims, characterized by that the spring element (20) is made of an elastic material, preferably a spring sheet.

13. Discharge device according to one of the preceding claims, characterized by that the conductor (37, 38) is attached to the spring element (20) by plastic deformation, preferably crimping.

14. Discharge device according to one of the preceding claims, characterized by thatthe conductor (37, 38) is formed with carbon fibers.

15. Discharge device according to one of the preceding claims, characterized by that the conductor (37, 38) is elongated, preferably rod-shaped.

16. Discharge device at least according to claim 2 and 15, characterized by that the conductors (37, 38) are arranged obliquely relative to one another.

17. Machine comprising a discharge device (10) according to one of the preceding claims.

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